/*
 * Copyright 2014 Broadcom Corporation
 *
 * SPDX-License-Identifier:     GPL-2.0+
 */

/*
 * Minimal semihosting implementation for reading files into memory. If more
 * features like writing files or console output are required they can be
 * added later. This code has been tested on arm64/aarch64 fastmodel only.
 * An untested placeholder exists for armv7 architectures, but since they
 * are commonly available in silicon now, fastmodel usage makes less sense
 * for them.
 */
#include <common.h>
#include <command.h>

#define SYSOPEN         0x01
#define SYSCLOSE        0x02
#define SYSREAD         0x06
#define SYSFLEN         0x0C

#define MODE_READ       0x0
#define MODE_READBIN    0x1

/*
 * Call the handler
 */
static noinline long smh_trap(unsigned int sysnum, void *addr)
{
        register long result asm("r0");
#if defined(CONFIG_ARM64)
        asm volatile ("hlt #0xf000" : "=r" (result) : "0"(sysnum), "r"(addr));
#elif defined(CONFIG_CPU_V7M)
        asm volatile ("bkpt #0xAB" : "=r" (result) : "0"(sysnum), "r"(addr));
#else
        /* Note - untested placeholder */
        asm volatile ("svc #0x123456" : "=r" (result) : "0"(sysnum), "r"(addr));
#endif
        return result;
}

/*
 * Open a file on the host. Mode is "r" or "rb" currently. Returns a file
 * descriptor or -1 on error.
 */
static long smh_open(const char *fname, char *modestr)
{
        long fd;
        unsigned long mode;
        struct smh_open_s {
                const char *fname;
                unsigned long mode;
                size_t len;
        } open;

        debug("%s: file \'%s\', mode \'%s\'\n", __func__, fname, modestr);

        /* Check the file mode */
        if (!(strcmp(modestr, "r"))) {
                mode = MODE_READ;
        } else if (!(strcmp(modestr, "rb"))) {
                mode = MODE_READBIN;
        } else {
                printf("%s: ERROR mode \'%s\' not supported\n", __func__,
                       modestr);
                return -1;
        }

        open.fname = fname;
        open.len = strlen(fname);
        open.mode = mode;

        /* Open the file on the host */
        fd = smh_trap(SYSOPEN, &open);
        if (fd == -1)
                printf("%s: ERROR fd %ld for file \'%s\'\n", __func__, fd,
                       fname);

        return fd;
}

/*
 * Read 'len' bytes of file into 'memp'. Returns 0 on success, else failure
 */
static long smh_read(long fd, void *memp, size_t len)
{
        long ret;
        struct smh_read_s {
                long fd;
                void *memp;
                size_t len;
        } read;

        debug("%s: fd %ld, memp %p, len %zu\n", __func__, fd, memp, len);

        read.fd = fd;
        read.memp = memp;
        read.len = len;

        ret = smh_trap(SYSREAD, &read);
        if (ret < 0) {
                /*
                 * The ARM handler allows for returning partial lengths,
                 * but in practice this never happens so rather than create
                 * hard to maintain partial read loops and such, just fail
                 * with an error message.
                 */
                printf("%s: ERROR ret %ld, fd %ld, len %zu memp %p\n",
                       __func__, ret, fd, len, memp);
                return -1;
        }

        return 0;
}

/*
 * Close the file using the file descriptor
 */
static long smh_close(long fd)
{
        long ret;

        debug("%s: fd %ld\n", __func__, fd);

        ret = smh_trap(SYSCLOSE, &fd);
        if (ret == -1)
                printf("%s: ERROR fd %ld\n", __func__, fd);

        return ret;
}

/*
 * Get the file length from the file descriptor
 */
static long smh_len_fd(long fd)
{
        long ret;

        debug("%s: fd %ld\n", __func__, fd);

        ret = smh_trap(SYSFLEN, &fd);
        if (ret == -1)
                printf("%s: ERROR ret %ld, fd %ld\n", __func__, ret, fd);

        return ret;
}

static int smh_load_file(const char * const name, ulong load_addr,
                         ulong *end_addr)
{
        long fd;
        long len;
        long ret;

        fd = smh_open(name, "rb");
        if (fd == -1)
                return -1;

        len = smh_len_fd(fd);
        if (len < 0) {
                smh_close(fd);
                return -1;
        }

        ret = smh_read(fd, (void *)load_addr, len);
        smh_close(fd);

        if (ret == 0) {
                *end_addr = load_addr + len - 1;
                printf("loaded file %s from %08lX to %08lX, %08lX bytes\n",
                       name,
                       load_addr,
                       *end_addr,
                       len);
        } else {
                printf("read failed\n");
                return 0;
        }

        return 0;
}

static int do_smhload(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
{
        if (argc == 3 || argc == 4) {
                ulong load_addr;
                ulong end_addr = 0;
                ulong ret;
                char end_str[64];

                load_addr = simple_strtoul(argv[2], NULL, 16);
                if (!load_addr)
                        return -1;

                ret = smh_load_file(argv[1], load_addr, &end_addr);
                if (ret < 0)
                        return 1;

                /* Optionally save returned end to the environment */
                if (argc == 4) {
                        sprintf(end_str, "0x%08lx", end_addr);
                        setenv(argv[3], end_str);
                }
        } else {
                return CMD_RET_USAGE;
        }
        return 0;
}

U_BOOT_CMD(smhload, 4, 0, do_smhload, "load a file using semihosting",
           "<file> 0x<address> [end var]\n"
           "    - load a semihosted file to the address specified\n"
           "      if the optional [end var] is specified, the end\n"
           "      address of the file will be stored in this environment\n"
           "      variable.\n");